Sound-amplifying device for sound reproducing and recording instruments



July 23, 1929. s, ODONNELL 1,72%007 souND AMPLIFYING DEVICE FOR SOUNDREPRODUCING AND RECORDING INSTRUMENTS Filed March 19, 1926 3Sheets-Sheet 1 y 23, 1929- P. s. ODONNELL 1,722,007

SOUND AMPLIFYING DEVICE FOR SOUND REPRODUCING AND RECORDING INSTRUMENTSFiled March 19. 1926 3 Sheets-Sheet 2 y 23, 1929- I P. s ODONNELL1,722,007

SOUND AMPLIFYING DEVICE FOR SOUND REPRODUCING AND RECORDING INSTRUMENTSFiled March 19, 1926 3 Sheets-Sheet 5 16 A; K mmwf-n o {a i [2 8 l y maPatented July 23, 1929.

v uN irao-fS TES 1,722,007 PATENT" oF FicE. f

' rA'rRIoK 'SH'AUGHNESSY ODONNELL, or LONDON, ENGLAND.

sounn ararnirymo DEVICE FOR scum) nrirnonucme AND RECORDINGinsrnumnn'rs.

H Application filed March 19, 1926, Serial No. 96,008, and in GreatBritain May 11, 1925.

This invention relates to, and has for its object the provision ofimprovements in, sound reproducing apparatus.

The invention consists broadly in the arrangemcnt according to which thevibrations of the sound to be reproduced are adapted to set upsympatheticvibrations in tuned gongs.

One embodiment of the invention is illustrated in the accompanyingdrawings and the 0 Same will now be described, it being unden' stoodthat the particular construction and arrangement illustrated aresusceptible of various modifications without departing from the scope ofthe invention as defined in the appended claims.

In these drawings Figure 1 is a side elevation of a loud speaker(particularly for use in connection with wireless apparatus) inaccordance with the invention, the casing thereof and certain otherparts being shown in section.

Figure 2 is an end elevation of the same looking from the left of Figure1.

' Figure 3 is a similar end elevation of all those parts to the right ofline X-X of Figure 1, certain of the parts being shown in chain dottedlines.

Figure 4 is a side elevation of a detail. Referring to the drawings theloud speaker therein illustrated comprises an electromagnet 1 thearmature 2 of which is adapted to vibrate in accordance with thevibrations of the sound to be reproduced. The vibrations ofthiselectromagnet are adapted to be transa mitted' to a diaphragm 3 ofconical shell formation through the medium of a transmission devicewhich. comprises two diamonds 4 and 5 which are insirrple contact withone another and which are in rigid relationship respectively with saidarmature 2 and said diaphragm i j Thus the diaphragm 3 is rigidlyand-coaxia-lly' mounted 'to a rod 6 extending" outwardly fromits apex,and this rod 5 carriesat its remote extremity the diamond 5.

The armature'2 carries a cup 7 which con tains the other diamond 4. Therod'G/is rebracketlfisothat the axis of said rodpasses througlithediamond 4 and the middle of the t armatiirefQZ. A' gspring 6 is providedfor with: respectto saidjsleeve in s ch. aiwgyit at; thediamond 5 ispresseddown-upon thetliainonde.

i The vibrations 03E the armature 2. are adapted to take place in asense at right angles to the rod 6 and thus the diamonds 1 and 5 tend torub one another in sense at right angles to the direction of thepressure between them. In practice the regularity of form of the twodiamonds results in an engagement between them such that the rod 6together with the diaphragm 3 vibrates transversely of its axis. Soundwaves are therefore emitted from saiddiaphragni. I

The bracket 9 and the electromagnet 1 are both supported from a commonbase 10 which consists of a glass disc and is suported. in spacedrelation from the back 11 of the loud speaker casing by means of foursupporting feet 12 spaced around its circumferential periphery. Theelectromagnet is mounted. to this base in the neighbourhood of itscentre and'the bracket 9 is made in the form of asleeve 8.

bridging member carrying the aforesaid The loud speaker casing is ofcylindrical t formation the back 11 thereof thus being disc shape.mounted therewithin at spaced intervals around the circumferential wallof said casing a number of tuned gongs 13 each of which represents adefinite musical note. These gongs are of spiral type and are located asThe front thereof is open and has shown in radial planes with respect tothe cylindrical casing and with their mounting points nearest the openend of the casing. They are mounted to an annular base 14extendingaround the inner periphery of the casing as shown. The gongsare partly isolated from one another by means of baffle plates 15- alsoarranged in radial planes.

-- These bafile plates come between the. outer halves only ofeach pairof the .gongs (i. e. the halves nearest the openend ofthe casing) andare formed so that they becamenarrower 'as theyappro'ach the. centre ofthecasingjnear to which theyv terminate. .They: also are mounted to'saidbase 15 andat their inner ciprocably mounted in a sleeve 8 carried by'aends carry anannulus 15.. l 1

Rigidly and c'oaxially' mountedv upon an extension of the sleeve 8and-betweenthe dia- 1 phra auxiliary diaphragx'ns are of, progressivelyvarying diametersand are arranged in spaced relation to one another withthe largest near- ,est the diaphragm 3 and the smallest nearest thebracket 9. 7

Between the cup 7 and the armature 2 and inrigid relation with both is-alass disc 17.

Extending between the disc s ape base 10 and the annular base 14 arefour'wooden rods 18. These rods are mounted to said base 10 by means ofblocks 18 cemented to, and overhanging the circumferential periphery.pf, said base, and arebolted to the base 14 as shown.

In operation the vibrations are transmitted as described by means of thediamond contact transmission device from the armature 2 to thediaphragm' 3. Sound waves are thus emitted from said diaphragm and passout through the open end of the casing past the gongs 13. The purity ofthe sound thus produced is enhanced on account of the said transmisiondevice and also as a result of the gon s 13. the transmission throughthe contactmg diamonds probably has the effect of making the vibrationsof the diaphragm 3 more nearly simple harmonic vibrations than are thevibrations of the armature 2 but this is not'certain. The gongs operateto break down echoes and false vibrations and to enhance the true notes.Each gong responds to its own proper note and tends to swamp falsenotes. The auxiliary diaphragms 16 and the disc 17 have the effect offurther increasing the mellowness and purity of the tone pro- .duced.The scientific explanation of this is not however quite clear. Theconnection between the base 10 and the base 14 by means of the rods 18has the eflect of increasing the sensitiven'ess of the gongs. Veryslightvibrations are transmittedfrom said base 10 to said base 14 andthus the gongs themselves are maintained in a slightly tremulous statein which they are more readily susceptible of sympathetic response totheir proper notes than when they are in a state 'of rest.

Describing now certain constructional details of the device, theelectromagnet 1 consists of a core .1 havingenergisable pole pieces 1"arranged one each side of the'armature 2 and adapted alternately toattract and repel the same. The armature 2 is mounted to a somewhatresilient bridging piece 2 one end of which is rigidly mounted to thebase 1 to which the core 1 is mounted and the otherend of which ismounted to said base in such away as to be adjustable with respectthereto in a vertical sense. Such adjustment is adapted to be efl'ectedby means'of an adjusting column passing through a hole in said base 10.Thebase 1? is secured to the base 10 by means of a suitable cement.

T e cup 7 is made in one unit with the disc '17 and with a suitablescrew 19 by which said.

unit is screwed to said armature 2. A washer 20 say ofebonite isinterposed between said screw 19 and the armature 2.

' clamped e is stamped into a pleated form. In the par-- ticularconstruction illustrated the former method is adopted and the framemembers of the diaphragm 3 are shown in Fig. 2 at 3". In this figure thebafiie plates 15 are shown superimposed over the radial frame members3". This is purely fortuitous and should not cause confusion. Thediaphragm 3 is provided with a boss 3 by which it is screwed onto theend of the rod 6 and said diaphragm v is also supported from theperiphery by means of strings 3 secured to the inner periphery of thecasing. The diaphragms 16 are formed with bosses 16. whereby they arespaced apart.

The four supporting feet 12 are provided with grooves as shown in whichthe edge of thebase 10 fits. These grooves are provided with rubber orlike pads 12 above and below the edge of said base.

No claim is made in this specification to the I construction of theconnection between the 95 loud speaker diaphragm and the actuatingmember thereof and comprising two hard jewels respectively connected tothe diaphragm and said member and arranged in simple contact with oneanother to transmit. the vibrations of said member to said diaphragm, assuch connection is described and claimed in my copending ap lication forLetters Patent of the United tates for Sound producing apparatus, filedMarch 19, 1926, Serial No. 96,010.- V

v No claim is made in this specification to a. loud speaker comprisingasound emitting diaphragm having an unclamped edge and a dampindiaphragm also having an un- 1 e located behind said sound emitas ,thisis described; and.

lication for Lettates for sound tin diaphragm cla lmed in my copendingap ters Patent of the United 7 reproducing apparatus, filed March 19,1926, 1

Serial No. 96,009.

What I. claim and desire to secure by Letters Patent is 1. Aloud speakercomprising a dia hragm for producing thesound waves, a puralityof tunedgongs mounted in the path which said sound waves are adapted to takevandbaflie plates located between adjacent pairs of said gongs. i

1 2. 'A 16 d speaker comprising a casing hav- 1 ing a sound wave exit, asound wave producing diaphragm located within said casing, a pluralityof tuned gongs of the spiral type mounted within said casing, said gongbe disposed adjacent said sound wave exit an 1 in planes approximatelyradial with respect to the approximate axis of saidsound wave exit andbattle plates located between adjacent pairs of said gongs in such a wayas only partially to isolate said pairs of gongs.

3. Aloud speaker comprising a cylindrical casing having one end open toprovide a sound wave exit, a sound wave producing diaphragm locatedwithin said casing, a plurality of tuned gongs of the spiral typemounted around the inner periphery of said casing in planesapproximately radial with respect to the axis-thereof and baflle plateslocated between adjacent pairs of said gongs in such a way as onlypartially to isolate said pairs of Q 4. A loud speaker according toclaim 3 wherein said bafile plates decrease in breadth as they approachsaid axis of the casing.

5. Aloud speaker comprising a casing having' a sound wave exit, aseparate sound wave producing diaphragm located within said casing and aplurality of tuned gongs rigidly mounted within said casing adjacentsaid sound wave exit and between said diaphragm and said wave exit. 1

6. Aloud speaker comprising'a cylindrical casing having one end open toprovide a sound wave exit, a separate sound wave producing diaphragmlocated within said casing and a plurality of tuned gongs of. the spiraltype mounted around the inner periphery of said casing and in a senseapproximately radially of the axis thereof, so as to be between saiddiaphragm and said sound wave exit. I In witness whereof I atfix my siature.

' PATRICK SHAUGHNESSY 'DONNELL.

